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Member postings for Jim Nic

Here is a list of all the postings Jim Nic has made in our forums. Click on a thread name to jump to the thread.

Thread: double acting oscillating cylinder engine
22/06/2019 15:40:37

Thanks for the info Geoff, I'll have a look for the drawing. If I decide to make it I'll drop you a message regarding the cylinder.

Jim

22/06/2019 14:16:24

That is indeed looking good.

I haven't got a double acting oscillator, neither have I got my next project lined up. This engine could well be my answer to both requirements. May I ask where you got the drawings from?

Jim

Thread: Thomas from Hornby
13/06/2019 16:44:29

? +1

Thread: The Workshop Progress Thread 2019
12/06/2019 10:35:42

Thanks for fixing my link Jason.

The engine is, as you say, a bit tight at the moment so will definitely ease a bit with more running. Also as it stands the cylinders and valve chest have no sealing so putting that in will reduce the air leakage and help. Another thing is that one of the return connecting rods is binding on the crank web which is the horrible clunking noise which can be heard which can't be helping with smooth running. There is plenty of work still to do to sort it before I even think about paint but since I haven't got my next project lined up that's not a problem.

Jim

11/06/2019 21:00:36

Got the Overcrank running and it is as good as I'd hoped for with plenty of action going on with even more to come when the governor (yet to be made) is fitted.

It runs smoothly at an air pressure of 5psi (my metrification does not extend to pressure) but does not like going under about 100 RPM at the moment. There is an annoyoing knock/rubbing noise which is coming from one of the return connecting rods which will have to be sorted. I know what the problem is but haven't looked in to a solution yet.

There should be a link to Utoob here but it hasn't appeared.  I'll try to get it sorted.

Overcrank run

Jim

 

 

Edited By JasonB on 12/06/2019 06:57:22

08/06/2019 13:33:15

Ouch! Hope all goes well for you.

Jim

08/06/2019 12:01:51

Geoff. The valves are conventional slide type.

Ian. The con rod centre portion was from a piece of steel into which I made a centre hole and tapped stud holes in each end.

conn rod 2.jpg

I then made a dead centre to avoid using a lathe dog on the part I needed to work.

conn rod 1.jpg

The centre part of the rod was then machined between centres with a rounded tool to give a good finish and radiused corners.

The brass bearings are made in the time honoured fashion of soft soldering two bits of brass together, drilling the requisite size hole for the crankshaft on the join line and then machining the joined piece to size and shape before melting the soft solder to give a split bearing.

Jim

07/06/2019 19:21:14

Thanks George, it's coming along.

What are you doing in hospital?

Jim

07/06/2019 14:54:19

More progress on Stew Hart's Overcrank engine. I looked at the connecting rod design and decided I preferred a different type of bearing arrangement closer to the original on the only picture I have of the full size engine at Quarry Bank Mill.

This is what I ended up with:

conn rod 4.jpg

With those made I have enough parts of the basic engine to get it to run.

basic engine 3.jpg

basic engine 2.jpg

The next step is to fettle and adjust everything until it is a runner then I can turn my attention to the governor.

The governor, a posh wooden base and a coat of paint should keep me occupied for a while yet.

Jim

Thread: Extreme turning
01/06/2019 10:50:12

Well it's on there right enough, Eric, how did you get a tool to it?

Jim

Thread: Hobbymat MD200
19/05/2019 20:42:17
Posted by SillyOldDuffer on 19/05/2019 20:19:49:

Difficult to describe why larger lathes make life easier, but they do!

Dave

For one thing, as has oft been said on here in response to the "What lathe?" question, you can make small parts on a big lathe but not big parts on a small lathe.

Jim

Thread: stamford show vandals
19/05/2019 15:03:16

Words fail me at the utter mindlessness of such destruction.

How do you motivate yourself to rebuild a layout after that and if you did I cannot imagine it would be shown in public for the enjoyment of others again.

May the culprits be severely punished, but I doubt that that will happen.

Jim

Thread: Adjustable workshop perching stool
13/05/2019 14:10:44

Looks very useful Stew, is that a lavatory seat you have on it? I manage with an assortment of 3 stools but not having the kit or expertise to weld I shall have to continue doing so.

Jim

Thread: Pressure gauge help needed please.
27/04/2019 18:14:25

Hi Bob

If you want something fairly quick there is always Jason's Jowitt engine, the complications being the shape of the cylinder block and the need to make the poppet valves and the spoked flywheels.

finished jowitt 7.jpg

More complex is the Corliss type engine, free plans from Model Engine Makers website. Complications are the operation of the valves and making the flywheel. Everything else should be a breeze for you.

corliss 1.jpg

My last suggestion depends on your budget. The Eastern & Anderson Grasshopper model from a castings set available from Polly Models for about £240 I believe.

dsc01612.jpg

Hope this has given you something to consider

Jim

Thread: The Chocolate Fireguard as designed by Mercedes Benz
26/04/2019 10:38:28

My Honda Jazz has a similar speed limit recognition system to Keith's Merc but has a display of the limit recognised by the camera. When I bought the car I thought it might be useful to have a reminder of what the limit was always on display in this day and age when limits change seemingly on a whim many times on most stretches of apparently similar road. However the display turns off after a minute or so of the car recognising a speed sign so there is no lasting reminder.

Even worse, the system can be set so that if the car recognises a speed limit sign it will not accelerate to a speed faster than that limit, which would be sensible if the car's camera and computer always correctly recognised the signs which is a long way from being the case.

The whole system has been turned off (after a lengthy trawl through a maze of menus).

Jim

Edited By Jim Nic on 26/04/2019 10:41:38

Thread: The Workshop Progress Thread 2019
03/04/2019 22:46:43

In my last post on the progress of Stew Hart's Overcrank design I had made the valve eccentrics (and the eccentric straps) which had to be fitted to the crankshaft centre section before assembling the shaft. I then thought that making up the shaft would naturally be the next operation. When I came to cut the 12mm dia bar to length for the main part I found that the exact length depended on the width of the flywheel and the output pulley hubs. Sooo the next task was to obtain a flywheel casting from Stuart Models and machine it and make a pulley and, while I was at it, a pulley for the governer belt.

flywheel 6.jpg

output 16.jpg

Then I assembled the crankshaft using my usual Loctite method but since this was a twin cylinder engine I also pinned the webs. The pins are fitted through the webs from one end, go through both the "big end" and the shaft section but stop short of protruding from the other end of the web.

crankshaft 6.jpg

And here is an assembly shot of the crankshaft in position before I had cut out the redundant pieces between the webs.

crankshaft 7.jpg

Next up I get to fit the laser cut crank return rods

return conn rods.jpg

Jim

Thread: Potty overcrank
29/03/2019 15:04:45

Well there's this one

vertical cross single 1.jpg

Jim

Thread: Scaling dimensions
25/03/2019 22:02:21

I scaled up this Mogens Kilde designed Double Diagonal engine by two by simply doubling the drawing dimensions and found that while most aspects looked OK at twice design size, the fasteners most definitely did not. Bigger - yes, but not twice as big. I actually used BA fastenings instead of the metric called for on the drawings and just chose sizes I thought would look right and took the view that for an air powered model whatever I chose would would be strong enough.

99 finished 1.jpg

99 finished 2.jpg

Jim

Edited By Jim Nic on 25/03/2019 22:04:23

Thread: The Workshop Progress Thread 2019
30/01/2019 17:16:29

I’ve not been well for a couple of months so there has been less progress on the Overcrank engine than normal.

This is the first engine I have built without the benefit of a build log or construction notes for guidance. My plan was to make the crankshaft next but luckily I had a close look at the drawings before I did and found that the valve eccentrics and crank centre bearing were on the shaft between the 2 throws.

eccentric 3.jpg

The bearing could have been made as a split shell but I couldn’t see how to make the eccentric sheaves work with a join in them. So the only way seemed to me to make them as normal

eccentric 2.jpg

and assemble them on the crankshaft before assembling and pinning the journals.

eccentric 4.jpg

Happy days, the valves seem to move as they should so now it's back to the plan and build the crankshaft.

Jim

Thread: Use of Colour on Drawings
16/01/2019 12:03:02

Jason

Firstly thanks for your consideration for the needs of your "customers".

My difficulty is sometimes visualising the shape of the part from the drawing so the addition of an occasional 3D image is welcome. The rendering of the intended result is also useful so I know where I am headed.

My preference of your options would be 1 or 2. Dimensioned in metric, on uncluttered A4 sheets in PDF format.

Jim

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